Buggy code:
public class AjTypeImpl < T > implements AjType < T > { private static final String ajcMagic = "ajc$" ; private Class < T > clazz ; private Pointcut [ ] declaredPointcuts = null ; private Pointcut [ ] pointcuts = null ; private Advice [ ] declaredAdvice = null ; private Advice [ ] advice = null ; private InterTypeMethodDeclaration [ ] declaredITDMethods = null ; private InterTypeMethodDeclaration [ ] itdMethods = null ; private InterTypeFieldDeclaration [ ] declaredITDFields = null ; private InterTypeFieldDeclaration [ ] itdFields = null ; private InterTypeConstructorDeclaration [ ] itdCons = null ; private InterTypeConstructorDeclaration [ ] declaredITDCons = null ; public AjTypeImpl ( Class < T > fromClass ) { } public String getName ( ) { } public Package getPackage ( ) { } public AjType < ? > [ ] getInterfaces ( ) { } public int getModifiers ( ) { } public Class < T > getJavaClass ( ) { } public AjType < ? super T > getSupertype ( ) { Class < ? super T > superclass = clazz . getSuperclass ( ) ; <START_BUG> return ( ( AjType < ? super T > ) ( new AjTypeImpl ( superclass ) ) ) ; <END_BUG> } public Type getGenericSupertype ( ) { } public Method getEnclosingMethod ( ) { } public Constructor getEnclosingConstructor ( ) { } public AjType < ? > getEnclosingType ( ) { } public AjType < ? > getDeclaringType ( ) { } public PerClause getPerClause ( ) { } public boolean isAnnotationPresent ( Class < ? extends Annotation > annotationType ) { } public < A extends Annotation > A getAnnotation ( Class < A > annotationType ) { } public Annotation [ ] getAnnotations ( ) { } public Annotation [ ] getDeclaredAnnotations ( ) { } public AjType < ? > [ ] getAjTypes ( ) { } public AjType < ? > [ ] getDeclaredAjTypes ( ) { } public Constructor getConstructor ( AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public Constructor [ ] getConstructors ( ) { } public Constructor getDeclaredConstructor ( AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public Constructor [ ] getDeclaredConstructors ( ) { } public Field getDeclaredField ( String name ) throws NoSuchFieldException { } public Field [ ] getDeclaredFields ( ) { } public Field getField ( String name ) throws NoSuchFieldException { } public Field [ ] getFields ( ) { } public Method getDeclaredMethod ( String name , AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public Method getMethod ( String name , AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public Method [ ] getDeclaredMethods ( ) { } public Method [ ] getMethods ( ) { } private boolean isReallyAMethod ( Method method ) { } public Pointcut getDeclaredPointcut ( String name ) throws NoSuchPointcutException { } public Pointcut getPointcut ( String name ) throws NoSuchPointcutException { } public Pointcut [ ] getDeclaredPointcuts ( ) { } public Pointcut [ ] getPointcuts ( ) { } private Pointcut asPointcut ( Method method ) { } public Advice [ ] getDeclaredAdvice ( AdviceKind ... ofType ) { } public Advice [ ] getAdvice ( AdviceKind ... ofType ) { } private Advice [ ] getDeclaredAdvice ( Set ofAdviceTypes ) { } private void initDeclaredAdvice ( ) { } private Advice [ ] getAdvice ( Set ofAdviceTypes ) { } private void initAdvice ( ) { } public Advice getAdvice ( String name ) throws NoSuchAdviceException { } public Advice getDeclaredAdvice ( String name ) throws NoSuchAdviceException { } private Advice asAdvice ( Method method ) { } public InterTypeMethodDeclaration getDeclaredITDMethod ( String name , AjType < ? > target , AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public InterTypeMethodDeclaration [ ] getDeclaredITDMethods ( ) { } public InterTypeMethodDeclaration getITDMethod ( String name , AjType < ? > target , AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public InterTypeMethodDeclaration [ ] getITDMethods ( ) { } private void addAnnotationStyleITDMethods ( List < InterTypeMethodDeclaration > toList , boolean publicOnly ) { } private void addAnnotationStyleITDFields ( List < InterTypeFieldDeclaration > toList , boolean publicOnly ) { } public InterTypeConstructorDeclaration getDeclaredITDConstructor ( AjType < ? > target , AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public InterTypeConstructorDeclaration [ ] getDeclaredITDConstructors ( ) { } public InterTypeConstructorDeclaration getITDConstructor ( AjType < ? > target , AjType < ? > ... parameterTypes ) throws NoSuchMethodException { } public InterTypeConstructorDeclaration [ ] getITDConstructors ( ) { } public InterTypeFieldDeclaration getDeclaredITDField ( String name , AjType < ? > target ) throws NoSuchFieldException { } public InterTypeFieldDeclaration [ ] getDeclaredITDFields ( ) { } public InterTypeFieldDeclaration getITDField ( String name , AjType < ? > target ) throws NoSuchFieldException { } public InterTypeFieldDeclaration [ ] getITDFields ( ) { } public DeclareErrorOrWarning [ ] getDeclareErrorOrWarnings ( ) { } public DeclareParents [ ] getDeclareParents ( ) { } private void addAnnotationStyleDeclareParents ( List < DeclareParents > toList ) { } public DeclareSoft [ ] getDeclareSofts ( ) { } public DeclareAnnotation [ ] getDeclareAnnotations ( ) { } public DeclarePrecedence [ ] getDeclarePrecedence ( ) { } public T [ ] getEnumConstants ( ) { } public TypeVariable < Class < T > > [ ] getTypeParameters ( ) { } public boolean isEnum ( ) { } public boolean isInstance ( Object o ) { } public boolean isInterface ( ) { } public boolean isLocalClass ( ) { } public boolean isMemberClass ( ) { } public boolean isArray ( ) { } public boolean isPrimitive ( ) { } public boolean isAspect ( ) { } public boolean isMemberAspect ( ) { } public boolean isPrivileged ( ) { } @ Override public boolean equals ( Object obj ) { }

Fix:
return superclass == null ? null : ( ( AjType < ? super T > ) ( new AjTypeImpl ( superclass ) ) ) ;